MLBPA conducting investigation

Major League Baseball's players' association is conducting an investigation into the role some agents might have played in the Biogenesis doping scandal that rocked the sport last year, several sources told ESPN.

The MLB Players Association, which certifies player agents, retained veteran Washington attorney Robert Muse to run the investigation several months ago, the sources said, and he and his staff are expected to issue a report within the next few weeks.

According to sources, who spoke on the condition of anonymity, the two primary subjects of the investigation have been CAA in Los Angeles, where agent Nez Balelo represents Ryan Braun, and the ACES agency out of Brooklyn, run by longtime agents Seth and Sam Levinson.

Braun, who plays for the Milwaukee Brewers, accepted a 65-game suspension for performance-enhancing drug use last year.

At least two other agencies are part of the probe as well, sources said. The investigation also has looked into charges of client poaching, according to two sources.

If the agents are found to have been complicit or to have violated their duties, they could face decertification, although the MLBPA's agent regulations also allow for lesser penalties.

MLBPA general counsel David Prouty declined to confirm the existence of the investigation, saying, "We don't comment on internal investigations or whether we're conducting them."

A spokesman for MLB described the investigation as "an internal union matter" and referred questions to the MLBPA.

Balelo and CAA did not return a call for comment, while ACES released a statement saying, "Biogenesis has been thoroughly investigated and there is no evidence of any wrongdoing on our part."

ACES came under the spotlight in 2012 when MLB discovered that Melky Cabrera, who tested positive for testosterone, tried to create a fake website as part of a plan to explain the failed test. Juan Carlos Nunez, the ACES agent who was working with Cabrera, was decertified after he was connected to the conspiracy. Nunez was later identified as a conduit between Biogenesis founder Tony Bosch and numerous ACES clients, including Cabrera, who were suspended for violating the PED policy. Of the 25 major and minor league players who were identified as Biogenesis clients -- not all were suspended -- 10 were ACES clients.

The union censured ACES last year for failing to supervise Nunez properly, but then-union executive director Michael Weiner also issued a statement saying, "We conducted a thorough investigation and concluded that none of the ACES principals were involved in the scheme and that there was no knowledge or involvement by Seth and Sam."

However, several sources familiar with the case said Muse's investigation is looking into whether the Levinsons were indeed aware of Nunez's work as a leg man for Bosch or his part in the Cabrera website.

Seth Levinson in the past has denied that he or his brother was aware of Nunez's activities. They described him as a consultant, although Nunez was certified by the union as an agent.

Muse is, by any standard, a heavyweight and has worked as a staff attorney or consultant on numerous congressional investigations, starting with Watergate, up through the Iran-Contra affair and the special Senate committee to investigate the response to Hurricane Katrina in 2005-06. He has been a partner at Stein, Mitchell, Muse, Cipollone and Beato since 1983.

Muse declined comment Thursday.